Damage-resistant gloves with breach-indicator function

ABSTRACT

The present invention relates to a multi-layered latex cover, particularly a glove, comprising a main body and a rim. The main body comprises an outer latex layer, an inner latex layer and an intermediate layer comprising particles. The rim essentially consists of the agglutinated outer and inner latex layer. The particles in the intermediate layer are chemically functionalized with a compound comprising hydrophobic groups. Prior to functionalization, the particles are characterized by a mean diameter of ≤100 μm and a surface comprising exposed OH groups. The invention further relates to a method of producing the multi-layered cover, comprising the steps of providing a former and sequentially immersing it in a first coagulator solution, a first latex dispersion, a particle suspension and a second latex dispersion.

The present invention relates to disposable, multi-layered gloves and toa method of producing the same. BACKGROUND

Disposable gloves have to meet many different, sometimes evenconflicting demands. Gloves worn by health care professionals,laboratory and emergency personnel provide a physical barrier coveringthe bare hand as a hygiene and contamination protection measure. Thegloves have to protect their wearer from direct skin contact withharmful substances and infectious agents. They have to be durable, butflexible and provide a good grip while not compromising the sense oftouch too much. The gloves should also be non-irritant to the skin.Certain gloves, in particular surgical gloves, have to be sterile andindividually wrapped. Since the gloves are frequently replaced, it isnecessary for them to be relatively inexpensive while still exhibiting ahigh quality.

A certain percentage of gloves manufactured in mass production exhibithole defects. To reduce the percentage of gloves with hole defects is animportant challenge. Holes can also occur after the production processthrough unauthorized tampering or by accidents while using the glove,e.g. via damage by scalpels or needles. Unfortunately, these holes areusually not easily visible and thus not immediately noticed. To increasesafety, a common approach is to don two gloves, one above the other.This however creates other problems, like slipping and sagging of theouter glove.

Double-layered gloves can provide the same physical barrier as wearingtwo gloves without the mentioned disadvantages. A very relevant featureof such a double-layered glove can be an indicator function thatimmediately notifies the wearer of a hole in one of the layers, e.g. bya visible signal.

Gloves usually consist of several agglutinated layers. These result frommultiple dipping processes and cannot be distinguished from a single,thicker layer. However, modifications exist. EP 0 561 651 A1 (alsopublished as U.S. Pat. Nos. 5,438,709 and 6,280,673) claims an efficientdipping process for a polyvinyl alcohol coating to achieve lubricioussurface properties of the gloves. US 2003/0124354 A1 describes thedipping of the former in various steps, either by dipping in the same ora different material, or by dipping into latex baths of differentcolour. This and any other US patent document cited in the presentspecification are incorporated by reference herein.

The integration of a perforation indicator, which warns the user in caseof breach, requires the spatial separation of the polymer layers.Methods of producing gloves with two separate layers are usually complexand expensive. Approaches to produce such latex articles in a singleprocess are exemplarily described in U.S. Pat. No. 5,965,276. Here,particles such as gentian violet are applied in an additional dippingstep in between the layers in order to separate the adjoining inner andouter layer. In another example, it proposes intermediate dipping intozinc stearate, claiming the same result. One problem is that thisprocess requires another dipping into a coagulator. Another problem isthat these substances are harmful to health. Since not being chemicallylinked to the latex layer, these substances may be stripped off orrinsed out. In case of breach of the glove, it may get in contact withthe skin and open surgery and put patients at risk.

In another approach to achieve perforation indication, dyedmicrocapsules are employed in an intermediate layer (US 2011/0287553).WO2007068873 proposes the use of silica particles to form theintermediate layer. While a procedure using silica particles producesthe desired effect of separating the layers, it fails to accomplish thequality behaviour of double gloving systems. A controlled application ofthe silica is difficult, the particles are not bound to the latex layersand their slight hydrophilicity does neither support the stabilizationin a suspension for dipping, nor does it allow to homogeneously applythe particles to the hydrophobic latex layers.

Based on the above-mentioned state of the art, the objective of thepresent invention is to provide a cost-effective, fast and reliablemethod to produce durable, damage-resistant gloves comprising abreach-indicator function. This problem is solved by the subject-matterof the independent claims.

DESCRIPTION OF THE INVENTION

The term “latex” in the context of the present specification relates toa rubbery polymer. Non-limiting examples of latex rubber include naturalrubber, caoutchouk, polyisoprene, nitrile-containing polymers, nitrilerubber, and polychloroprene.

The term “latex dispersion” relates to an aqueous polymer dispersion ofone of the above named latices, that can be solidified.

Multi-Layered Cover

According to a first aspect of the invention, a multi-layered shapedcover is provided. In particular embodiments, the cover is shaped like ahuman hand and may serve as a glove. The multi-layered cover comprises amain body and a rim. The main body comprises an outer latex layer and adistinct inner latex layer separated from but adjacent to the outerlayer on an inner side of the cover where the cover is glove-shaped. Anintermediate layer comprising particles separates the outer and theinner layer. The rim essentially consists of the agglutinated first andsecond latex layer (FIG. 1). In the non-functionalized state, theparticles are characterized by

-   -   a mean diameter of 100 μm and    -   a surface comprising exposed OH groups.

In the intermediate layer, the particles are chemically functionalizedwith a compound comprising hydrophobic groups.

Particles

In certain embodiments, the particles are micro particles. In certainembodiments, the particles are nano particles.

In certain embodiments, the particles are organic particles. In certainembodiments, the particles are organic particles comprising oressentially consisting of a material selected from polystyrene,polylactides (PLA), polyglycolides (PGA), poly(lactide co-glycolides)(PLGA), polyanhydrides, polyorthoesters, polycyanoacrylates,polycaprolactone, polyglutamic acid, polymalic acid, poly(N-vinylpyrrolidone), poly(methyl methacrylate), poly(vinyl alcohol),poly(acrylic acid), poly acrylamide, poly(ethyleneglycol) andpoly(methacrylic acid).

In certain embodiments, the particles are inorganic particles. Incertain embodiments, the particles are inorganic particles comprising oressentially consisting of a material selected from silica, titaniumdioxide, zirconium dioxide, iron oxide, gold, silver, gadolinium,magnesium fluoride, strontium fluoride, or similar fluorides.

In certain embodiments, the particles comprise or essentially consist ofsilica, titanium dioxide or zirconium dioxide. In certain embodiments,the particles comprise or essentially consist of silica.

In certain embodiments, the particles are characterized by a meandiameter of ≤10 μm. In certain embodiments, the particles arecharacterized by a mean diameter of ≤1 μm. In certain embodiments, theparticles are characterized by a mean diameter of ≤0.1 μm.

In certain embodiments, the particles are melamine resin particles. Incertain embodiments, the particles are polystyrene particles. In certainembodiments, the particles are polymethylmethacrylate particles. Incertain embodiments, the particles are zeolitic imidazolate frameworks(ZIFs). ZIFs are composed of tetrahedrally-coordinated transition metalions (e.g. Fe, Co, Cu, Zn) connected by imidazolate linkers. In certainembodiments, the particles are carbon nanotubes. In certain embodiments,the particles are graphene particles.

In certain embodiments, the particles are silica particles, particularlysilica particles having a mean diameter of ≤50 μm, particularly silicaparticles having a mean diameter of ≤25 μm, more particularly silicaparticles having a mean diameter of ≤15 μm. In certain embodiments, thesilica particles have a mean diameter of 0.01 μm≤d≤1 μm. In certainembodiments, the silica particles are a mixture of smaller particles(0.01 μm≤d≤1 μm) and bigger particles (5 μm≤d≤25 μm).

The particles act as “spacers” between the latex layers and thus ensureseparation between the two layers (FIG. 3). Another advantage of theparticles is that they can add protection against stabs or cuts, sincethey are significantly harder than latex. The particles cover thesurface of the first latex covered former until immersion depth d₃.

In certain embodiments, the particles, irrespective of material, have amean diameter of ≤15 μm. In certain embodiments, the particles have amean diameter of 10 μm. In certain embodiments, the particles have amean diameter of 0.01 μm≤d≤0.1 μm. In certain embodiments, the particleshave a mean diameter of 0.1 μm≤d≤1 μm. In certain embodiments, theparticles are a mixture of smaller particles (0.1 μm≤d≤1 μm) and biggerparticles (5 μm≤d≤25 μm). A particle diameter <10 μm increases particlestability in suspension.

In certain embodiments, the particles are characterized by a meandiameter of ≤100 μm. In certain embodiments, the particles arecharacterized by a mean diameter of 10 μm to 100 μm. In certainembodiments, the particles are characterized by a mean diameter of 20-50μm. In certain embodiments, the particles have a mean diameter of ≤25μm. Particles of the sizes mentioned in the range of 1 to 100 μm,particularly from 20 to 50 μm, can bring advantages in certainembodiments by creating larger cavities between the layers, facilitatingthe flow of liquid between the layers in the event of a breach.

In certain embodiments, the particles are coloured. Coloured particlesincrease the visibility of a perforation of the outer layer (indicatorfunction).

The term “mean diameter” with regard to the particles particularlyrefers to the arithmetic mean or to the median of the diameterdistribution of the particles. Such mean size may be determined bymethods known to the skilled person such as, for example, by scanningelectron microscopy, static or dynamic light scattering (SLS, DLS) orsize-exclusion chromatography. If no other method is explicitlymentioned, particle sizes given herein to define the invention aredeemed to be determined by dynamic light scattering.

In certain embodiments, the particles are characterized by a surfacecomprising exposed OH groups having a density of 1-10 m/nm². In certainembodiments, the particles are characterized by a surface comprisingexposed OH groups having a density of 2-5 /nm². In certain embodiments,the particles are characterized by a surface comprising exposed OHgroups having a density of 2.2-2.5/nm². In certain embodiments, theparticles are characterized by a surface comprising exposed OH groupshaving a density of 2.2/nm².

In certain embodiments, the particles are characterized by a surfacecomprising exposed SiOH (silanol) groups having a density of 2-5/nm². Incertain embodiments, the particles are characterized by a surfacecomprising exposed SiOH groups having a density of 2.2-2.5/nm².

Free silanol groups can be quantified by various methods. By way ofnon-limiting example, methods for determining the SiOH concentrationare: chlorinating ≡SiOH, reacting ≡SiOH with phenyllithium, diazomethaneand alkylmagnesium halides, reacting ≡SiOH with B₂ H₆, reacting ≡SiOHwith LiAlH₄, infrared spectroscopy. A precise and straightforward methodof quantifying the SiOH concentration on the particle surface isreacting particles with LiAlH₄ in accordance with the following equationin the presence of diglyme:

4 SiOH+LiAlH₄→LiOSi+Al(OSi)₃+4 H₂

This method involves measuring pressure to determine the amount ofhydrogen formed and thus the silanol group density. As the hydride ion,functioning as an aggressive agent, is very small and highly reactive,all the silanol groups on the surface are detected, including thebridged ones. Unless stated otherwise, Si—OH densities stated herein aredetermined by this method

Particle Functionalization

The particles are functionalized with hydrophobic groups, or hydrophobicand hydrophilic groups. Functionalized particles may be in the form ofmonofunctional particles (functionalized with a specific hydrophobicgroup), multifunctional particles (functionalized with differenthydrophobic, or hydrophobic and hydrophilic groups), or may be providedas a particle mixture comprising different monofunctional particles.

Functionalization with hydrophobic groups/with a hydrophobic layerenables/assists adhesion to the first latex covered former duringapplication of the particles and anchoring/coupling to the latex duringsubsequent vulcanization. In certain embodiments, this is effected bythe formation of covalent bonds between functionalized particle andlatex.

Linking the particles to the latex ensures that in the case of breach ofa latex layer the structural integrity of the product is granted and theparticles are not released.

In certain embodiments, the particles are functionalized with a compoundcomprising unsaturated groups or sulfur, in particular with a compoundselected from 7-octenyltrimethoxysilane, 5-hexenyltrimethoxysilane,3-mercaptopropyltrimethoxysilane, 3-aminopropyl)triethoxysilane,tris(2-methoxyethoxy)(vinyl)silane, allyltrimethoxysilane,3-(aminopropyl)triethoxysilane, hexadecyltrimethoxysilane,vinyltrimethoxysilane, triethoxyvinyl silane,3-trimethoxysilylpropane-1-thiol,bis[3-(triethoxysilyl)propyl]tetrasulfide, 3-(methacryloxypropyl)trimethoxysilane and 3-N-(3-triethoxysilylpropyl)gluconamide.

In certain embodiments, the functionalized particles have a hydrophobicparticle surface.

In certain embodiments, the particles are additionally functionalizedwith a compound comprising hydrophilic groups. In certain embodiments,the particles are additionally functionalized with a compound comprisinghydrophilic groups selected from polyethylene glycol,N-(3-triethoxysilylpropyl)gluconamide and/or 3-[methoxy(polyethyleneoxy)propyl]trimethoxysilane.

Functionalization with hydrophilic groups/with a hydrophilic layerimproves the dispersibility of the particles in water and stabilizes theparticles in an aqueous suspension. It also acts as a coagulating agentduring the subsequent latex dipping, facilitating an even application ofthe latex layer on top.

Functionalization with hydrophilic groups/with a hydrophilic layer alsoimproves the indicator function of the intermediate layer. A hydrophilicparticle surface enables influx of aqueous liquids into the intermediatelayer, such that the intermediate layer acts as a liquid reservoir incase of breach. By increasing the wettability in water, the water (ormoisture from the environment) is sucked into the intermediate layermore efficiently and thereby the visible spot increases faster andspreads to a larger area. The filling level of the liquid reservoirbecomes more apparent, when the inner layer is of dark colour.

Using the measuring instructions described in the examples section, theeffect of differently modified particles in the intermediate layer onthe effectiveness of the perforation indicator can be assessed. If avisibly discernible area indicating breach by change of colour of 50 mm²forms within 100 sec, this is considered a good perforation indicator(FIG. 9).

In certain embodiments, the functionalized particles have an amphiphilicparticle surface.

An amphiphilic particle surface has advantages of both a hydrophobicparticle surface and an hydrophilic particle surface. It allowsstabilization or sufficient stabilization of the particles in an aqueoussuspension, adhesion to the first latex covered former, serves ascoagulating agent for application of the second latex cover, and assistschemical bonding to the latex cover during vulcanization. Amphiphilicparticles enable an influx of aqueous liquids in case of breach, suchthat the intermediate layer acts as a liquid reservoir.

In certain embodiments, the functionalized particles are functionalizedwith at least two different substances.

The first substance is selected from substances suitable for yielding ahydrophobic surface. In certain embodiments, the first substance isselected from substances containing unsaturated groups or sulfur, moreparticularly a substance selected from 7-octenyltrimethoxysilane,5-hexenyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane,3-aminopropyl)triethoxysilane, tris(2-methoxyethoxy)(vinyl)silane,allyltrimethoxysilane, 3-(aminopropyl)triethoxysilane,hexadecyltrimethoxysilane, vinyltrimethoxysilane, triethoxyvinylsilane,3-trimethoxysilylpropane-1-thiol,bis[3-(triethoxysilyl)propyl]tetrasulfide,3-(methacryloxypropyl)trimethoxysilane and3-N-(3-triethoxysilylpropyl)gluconamide.

The second substance is selected from substances suitable for yielding ahydrophilic surface. In certain embodiments, the second substance isselected from polyethylene glycol andN-(3-triethoxysilylpropyl)gluconamide or3-[methoxy(polyethyleneoxy)propyl]trimethoxy silane.

In certain embodiments, the particles comprise an alkylsilane surfacecoating. Within the context of the present specification, the term“silanes” refers to saturated chemical compounds consisting of askeletal structure of silicon atoms (silicon backbone) and hydrogen. Thesilicon atoms are linked to each other as the tetrahedral centers ofmultiple single bonds. Each silicon atom has four bonds (either Si—H orSi—Si bonds), and each hydrogen atom is joined to a silicon atom (H—Sibonds). Commercially available silanes are synthetically derived. Withinthe context of the present specification, the term “alkylsilanes” refersto chemical compounds derived from silanes containing one or more alkylgroups. Non-limiting examples of alkylsilanes are methylsilane,trimethyl(trifluoromethyl)silane, trimethylsilanecarbonitrile,dimethylsilane, trimethylsilane, triethylsilane, tetramethylsilane andhexamethyldisilane.

In certain embodiments, silanes with long hydrophobic groups andunsaturated bonds such as tris(2-methoxyethoxy)(vinyl)silane,7-octenyltrimethoxysilane, 5-hexenyltrimethoxysilane orallyltrimethoxysilane are used to achieve hydrophobicity of theparticles. The vinyl group is used for covalent bonding of the particlesto the polyisopren chain during vulcanization.

In certain embodiments, silanes comprising a thiol moiety (—SH), e.g.3-mercaptopropyltrimethoxysilane, are used to achieve hydrophobicity ofthe particles. The thiol (mercapto) moiety is used for covalentattachment of the particles to the polyisoprene chain duringvulcanization.

In certain embodiments, the particles are silica particles. In certainembodiments, the silica particles comprise an alkylsilane surfacecoating. An exemplary protocol for the functionalization of silicaparticles with tris(2-methoxyethoxy)(vinyl)silane as silane is given inthe examples section below.

In certain embodiments, different monofunctional silica particles areapplied subsequently or simultaneously (as a mixture).

An exemplary protocol for the functionalization of silica particles witheither PEG or silanes is given in the examples section below.

In certain embodiments, hydrophilic monofunctional silica particles(functionalized with a specific hydrophilic group) are additionallyfunctionalized with hydrophobic silanes, resulting in multifunctionalparticles that are functionalized with hydrophobic and hydrophilicgroups.

In certain embodiments, silica particles functionalized with PEG,N-(3-triethoxysilylpropyl)gluconamide or3-[methoxy(polyethyleneoxy)propyl]trimethoxysilane (hydrophilic) areadditionally functionalized with hydrophobic silanes, particularly witha hydrophobic silane selected from methylsilane,trimethyl(trifluoromethyl)silane, trimethylsilanecarbonitrile,dimethylsilane, trimethylsilane, triethylsilane, tetramethylsilane,hexamethyldisilane, tris(2-methoxyethoxy)(vinyl)silane,7-octenyltrimethoxysilane, 5-hexenyltrimethoxysilane,3-mercaptopropyltrimethoxysilane and/or allyltrimethoxysilane. Thissecond functionalization results in multifunctional particles that arefunctionalized with hydrophobic and hydrophilic groups.

In certain embodiments, the particles are multifunctional particles thatare functionalized with hydrophobic and hydrophilic groups. In certainembodiments, the particles are bifunctional particles that arefunctionalized with hydrophobic and hydrophilic groups. In certainembodiments, the particles are multifunctional or bifunctional particlesfunctionalized with PEG and silanes, particularly with PEG and a silaneselected from methylsilane, trimethyl(trifluoromethyl)silane,trimethylsilanecarbonitrile, dimethylsilane, trimethylsilane,triethylsilane, tetramethylsilane, hexamethyldisilane,tris(2-methoxyethoxy)(vinyl)silane, 7-octenyltrimethoxysilane,5-hexenyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane,bis[3-(triethoxysilyl)propyl]tetrasulfide and/or allyltrimethoxysilane(FIG. 8).

In certain embodiments, silica particles are functionalized with PEG anda hydrophobic silane, in particular vinylsilane.

An exemplary protocol for the functionalization of silica particles withboth PEG and silanes is given in the examples section below.

In certain embodiments, the PEG has a molecular weight of 200. Incertain embodiments, the PEG has a molecular weight of 2000. In certainembodiments, the PEG has a molecular weight of 10,000. In certainembodiments, the PEG has a molecular weight of 20,000. In certainembodiments, the PEG has a molecular weight of more than 20,000. Incertain embodiments, a mixture of PEG with different molecular weight isused. In certain embodiments, the PEG is a monodisperse PEG (mdPEG).

In certain embodiments, the silane istris(2-methoxyethoxy)(vinyl)silane. In certain embodiments, the silaneis allyltrimethoxysilane. In certain embodiments, the silane is3-(aminopropyl)triethoxysilane. In certain embodiments, the silane ishexadecyltrimethoxy silane. In certain embodiments, the silane isvinyltrimethoxysilane. In certain embodiments, the silane istriethoxyvinylsilane. In certain embodiments, the silane is3-trimethoxysilylpropane-1-thiol. In certain embodiments, the silane isbis[3-(triethoxysilyl)propyl]tetrasulfide. In certain embodiments, thesilane is 3-(methacryloxypropyl)trimethoxysilane. In certainembodiments, the silane is3-[methoxy(polyethyleneoxy)propyl]trimethoxysilane. In certainembodiments, the silane is N-(3-triethoxysilylpropyl)gluconamide.

In certain embodiments, particles functionalized with silane arechemically linked to the first latex layer. The former covered with thefirst latex layer is dipped into the prepared particle suspension. Theparticles adhere to the latex. The adhesion is increased due to thehydrophobicity of the silane coated particles. Subsequently, thefunctional groups on the outer surface of the particles are removed bydipping the latex and particle covered former into a sodium hydroxidesolution (1 mol l⁻¹). To clean the particle-covered surface from thesolution, it is dipped into a washing solution, which can be water orethanol or a mixture thereof. A sample with a similarly treated latexsurface is shown in FIG. 6. As a result, the silica particles surface iscovered with Si—O—H-groups and thereby regains their hydrophilicity onthe outer side. The particles outer surface functionalization is erased.When dipping into the second latex dispersion, sticking or adhesion ofthe particles to the second latex layer is prevented. The result is amulti-layered cover with particles linked to the first latex layer.

In certain embodiments, multifunctional particles are chemically linkedto the first or second (inner and/or outer) latex layer. The particlesare linked to the face of the latex facing the inner (intermediate)layer. The former covered with the first latex layer is dipped into theprepared particle suspension. The particles adhere to the latex and arechemically linked to the latex during vulcanization. Due to theirhydrophilic functionalities, the particles optimize the surface forwettability. That way, good perforation indication is ensured. Thecontact angle with water for treated latex surfaces are shown in FIG.10. A contact angle <90° is required for the perforation indicator towork; smaller contact angles of <45° are desirable. For the perforationindicator to perform within a reasonable amount of time, said contactangles are to be reached within a small amount of time, i.e. 10 s.

In certain embodiments, the silica particles are chemically linked tothe second latex layer using silanes with hydrophobic groups. In certainembodiments, these silanes are tris(2-methoxyethoxy)(vinyl)silane or7-octenyltrimethoxysilane. In certain embodiments, the silica particlesare chemically linked to the second latex layer using unsaturated bonds.In certain embodiments, the silica particles contain amine groups forchemical attachment.

In certain embodiments, (3-aminopropyl)triethoxysilane-coated particlesare covalently linked to the latex surface in an extra step. UsingUV-radiation, 5-azido-2-nitrobenzoic acid n-hydroxysuccinimide ester isphoto-crosslinked to the polyisopren's unsaturated bonds. The suchfunctionalized polyisopren is exposed to the coated particles, resultingin the formation of bonds between the 5-azido-2-nitrobenzoic acidn-hydroxysuccinimide ester and the amine group.

To summarize, particles entrapped by elastomer layers manufactured viadip coating ideally

-   -   are stabilized in a preferably aqueous suspension for initial        application to a latex layer,    -   adhere to the latex layer during dip coating,    -   act as a coagulator during subsequent latex dipping,    -   bond to the latex for safety purpose, and    -   support liquid flow within the particle layer and enable a        perforation indicator.

General

In certain embodiments, the multi-layered cover is characterized by athickness of 100 μm to 800 μm uniformly extending across its entiredimensions.

Together, the outer latex layer and the inner latex layer have athickness of at least 100 μm extending across the entire dimensions ofthe multi-layered cover. In certain embodiments, the outer and the innerlatex layer are both characterized by a thickness of 50 μm uniformlyextending across their entire dimensions. In certain embodiments, theouter and the inner latex layer are both characterized by a thickness of30 μm to 70 μm, in particular 40 μm to 60 μm, uniformly extending acrosstheir entire dimensions, while together, they exhibit a thickness of atleast 100 μm. In certain embodiments, the outer latex layer ischaracterized by a thickness of 40 μm uniformly extending across itsentire dimensions and the inner latex layer is characterized by athickness of 60 μm uniformly extending across its entire dimensions. Incertain embodiments, the outer latex layer is characterized by athickness of 60 μm uniformly extending across its entire dimensions andthe inner latex layer is characterized by a thickness of 40 μm uniformlyextending across its entire dimensions.

In certain embodiments of this aspect of the invention, the outer latexlayer is characterized by a thickness of 100 μm to 500 μm uniformlyextending across its entire dimensions and the inner latex layer ischaracterized by a thickness of 80 μm to 300 μm uniformly extendingacross its entire dimensions. In certain embodiments of this aspect ofthe invention, the outer latex layer is characterized by a thickness ofapprox. 200 μm uniformly extending across its entire dimensions and theinner latex layer is characterized by a thickness of approx. 100 μmuniformly extending across its entire dimensions.

Within the scope of the present invention are also latex covers that arefortified at certain positions, such as—in instances where the latexcover is a glove—the inner and outer surfaces of the fingers with orwithout the tips or the thenar eminence (the area at the base of thethumb), and/or the palm of the hand. In these positions, the thicknessof the latex layers, in particular of the outer latex layer, may exceedthe thickness that extends across the remaining dimensions of the latexcover. In certain embodiments, the thickness in these fortified areas isapprox. 1.5×the thickness in other parts. In certain embodiments, thethickness in these fortified areas is approx. twice the thickness inother parts. In certain embodiments, increasing the thickness at certainpositions is achieved by local application of an additional amount oflatex solution. In certain embodiments, the increase in thickness isachieved by local application of a coagulant solution with a higherconcentration of coagulator than said first (or said second) coagulatorliquid, which leads to the formation of a thicker latex layer (comparediagram A). The application of the coagulant solution can be applied orremoved in a dipping process and with tissue/brush.

In certain embodiments, outer layer and the inner latex layer areagglutinated at discrete regions. In certain embodiments, the discreteregions are regions of 1 mm² to 5 cm² at each fingertip. In certainembodiments, the discrete regions are regions of 4 mm² to 2.5 cm². Incertain embodiments, the discrete regions are regions of 9 mm² to 1 cm²at each fingertip. In certain embodiments, the discrete regions areregions of approx. 25 mm² at each fingertip.

In certain embodiments, the discrete regions form patterns, signs,characters or numbers to indicate the size of the gloves, the lotnumber, the date of production or expiration, labels of authorities orcompany logos.

In certain embodiments, the intermediate layer comprises a plurality oflayers. The plurality of layers within the intermediate layer comprisespairs of a particle layer and a latex layer. The particle layercomprises particles that chemically functionalized with a compoundcomprising hydrophobic groups. Prior to their functionalization, theparticles have a mean diameter of 100 μm and a surface comprisingexposed OH groups.

In certain embodiments, the intermediate layer comprises a plurality ofdouble layers as described in the previous paragraph, and the innerlatex layer, or the inner latex layer and adjacent latex layers of theintermediate layer are intentionally perforated. This results in areservoir able to absorb aqueous liquid. In instances where themulti-layered cover is a glove, a perforated inner latex layer offersthe advantage that moisture (e.g. sweat) can be transported from theskin to the intermediate layer of the glove via capillary action. Thisprevents slipping of the glove and thus improves grip security andsafety of all actions performed while using the glove. The skilledperson is aware that such a glove only has a perforation indicatingfunction when it comprises two intact latex layers separated by anintermediate layer comprising particles.

In certain embodiments of this aspect of the invention, themulti-layered cover comprises a means for breach indication (a breachindicator function). The breach indicator function notifies the user ofthe multi-layered cover (e.g. the person wearing a double-layered latexglove according to the invention) of a perforation in one of the latexlayers, usually the outer layer. By way of non-limiting example, thebreach indicator function can be triggered by capillary action betweenthe outer and the inner latex layer after perforation of one layer. Theoccurrence of a breach can be communicated in the form of a visibleeffect (agglutination of the outer and inner latex layer, describedabove) or in the form of an acoustic signal (enabled by RFID technology,see below).

In certain embodiments of this aspect of the invention, themulti-layered cover comprises a means for position tracking. The meansfor position tracking notifies the user of the multi-layered cover (e.g.the person wearing a double-layered latex glove according to theinvention) if the multi-layered cover is located outside a predeterminedarea. This can be communicated in the form of an acoustic signal(enabled by RFID technology, see below).

In certain embodiments of this aspect of the invention, the intermediatelayer comprises an RFID (radio frequency identification) tag. In thecontext of the present specification, an RFID tag is a device that canprovide information about an object (to which the tag is attached) to anRFID reader using electromagnetic fields. The RFID reader transmits anencoded radio signal to interrogate the tag. The RFID tag receives themessage and then responds with its identification and specificinformation. In the context of the present specification, an RFID tagcan be used to obtain information on the perforation of the outer latexlayer (breach indicator function). The tag can also be used to obtaininformation on the position of the protective latex cover. This isimportant in instances where a certain latex cover (e.g. a surgicalglove used during an operation) may not leave a certain area (e.g. asterile zone). The user can be notified about a change in position or aperforation by an acoustic signal. This can be an advantage if anoptical signal is less likely to be noticed (e.g. soiled gloves).

In certain embodiments of this aspect of the invention, said outer layerand said inner latex layer are agglutinated at discrete regions, inparticularly at regions of approx. 25 mm² at each fingertip.

Glove

According to a second aspect, the invention provides a glove comprisingor essentially consisting of a multi-layered cover according to thefirst aspect of the invention.

Method

According to a third aspect, the invention provides a method ofproducing a multi-layered cover. The method comprises the steps of:

-   -   a. Providing a former. The former is the negative of the latex        cover that is to be produced, and resembles in shape the object        or body part that is to be covered by the latex cover when the        latter is employed in practice. In certain embodiments, the        former is made of glazed or unglazed ceramic.    -   b. Immersing the former in a first coagulator liquid to an        immersion depth d₁, then retracting and drying the former. The        different immersion depths during the dipping process are        illustrated in FIG. 1.    -   c. Immersing the former in a first latex dispersion to an        immersion depth d₂, then retracting and drying the former. This        step yields a first latex covered former. The latex layer        established in this step is the first latex layer (FIG. 2:        numeral 3).    -   d. Applying chemically functionalized particles to the first        latex covered former to an immersion depth d₃. This step yields        a particle treated former. The particles are chemically        functionalized with a compound comprising hydrophobic groups.        -   In the non-functionalized state, the particles are            characterized by            -   a mean diameter of 100 μm and            -   a surface comprising exposed OH groups. In certain                embodiments, the latex covered former is immersed in a                suspension of functionalized particles to an immersion                depth d₃, then it is retracted and dried. In certain                embodiments, the latex covered former is subsequently                immersed in two or more different particle suspensions                to an immersion depth d₃, then it is retracted and                dried. These different particle suspensions may each                comprise particles of different material and/or size, or                particles functionalized with various groups. In certain                embodiments, the suspension of particles comprises 9.4%                (v/v) particles in water or ethanol or a mixture of                water and ethanol. In certain embodiments, immersion in                the suspension of particles is carried out for 1 to 10                seconds, in particular 2 to 3 seconds at room                temperature.        -   In certain embodiments, the dipping process in the            suspension is repeated, with or without intermediate            heating.        -   In certain embodiments, the latex covered former is immersed            in a second coagulator liquid to an immersion depth d₃, then            it is retracted, the particles are applied to the immersed            surface, and the particle treated former is dried.    -   e. Immersing the particle treated former in the second latex        dispersion to an immersion depth d₄, then retracting and drying        the particle treated former. This step yields a second latex        covered former. The latex layer established in this step is the        second latex layer (FIG. 2: numeral 5).        -   The immersion depths during the dipping process are            specified as d₁≥d₂>d₃ and d₁≥d₄>d₃ (FIG. 1).        -   d₁≥d₂: The complete former surface to be immersed in the            first latex dispersion is pre-treated with the first            coagulation liquid. This supports homogenous hardening of            the latex and (since the coagulation liquid comprises a            former release agent) ensures an easy (future) removal of            the multi-layered cover from the former.        -   d₂>d₃ and d₄>d₃: Only part of the first latex layer is            treated with silica particles. The complete first latex            layer—comprising a treated area and a non-treated area—is            immersed in the second latex dispersion. In the treated            area, agglutination of the first and second latex layers is            prevented, resulting in two separate latex layers (lower            circle in FIG. 2). In the non-treated area, the first and            second latex layers agglutinate and form a single latex            layer (upper circle in FIG. 2).        -   The rim is defined by the dipping depths of d₂, d₃ and d₄.            In case of d₂=d₄, the rim exclusively consists of            agglutinated layers. Agglutinated and separated areas are            also illustrated in FIG. 4.        -   In case of d₂ >d₄, said rim is extended by a single latex            layer, resulting from dipping in the first latex dispersion.            In case of d₂<d₄, said rim is extended by a single latex            layer, resulting from dipping in the second latex            dispersion. In case of d₂≠d₄, said single latex layer has            the colour of the respective dispersion.    -   f. Applying a coating to the second latex covered former,        yielding a coated former. This step enables easy donning of the        latex cover that is produced by the inventive method. By way of        non-limiting example, this step comprises procedures selected        from applying talcum powder, applying starch, coating with a        polymer or performing a mild chlorination step. Coating with a        polymer comprises adding a thin polymer layer which lubricates        the latex cover. Chlorination comprises exposure of the second        latex covered former to chlorine (as a chlorine acid mixture or        as a chlorine gas) to make the latex harder and slicker.    -   g. Removing the applied layers from the coated former, thereby        turning the first latex layer into the outer latex layer and the        second latex layer into the inner latex layer. This step yields        the multi-layered cover according to the invention.

In certain embodiments, the particles are characterized by a surfacecomprising exposed OH groups having a density of 2-5 /nm². In certainembodiments, the particles are characterized by a surface comprisingexposed OH groups having a density of 2.2-2.5 /nm²

In certain embodiments, step d is effected by immersing the first latexcovered former in an aqueous suspension comprising chemicallyfunctionalized particles to an immersion depth d₃. In certainembodiments, the concentration of chemically functionalized particles inthe aqueous suspension is 0.5 mol %.

In certain embodiments, the chemically functionalized particles areapplied in step d from an aqueous suspension with a concentration of 0.2and 7 mol/L, particularly approx. 1 mol/L by adding a latex dispersion(40-80 wt %, particularly 60 wt % solid content) with a volume ratio ofsuspension to latex dispersion of less than 1:20. Latex being a part ofthe particle suspension can aid in facilitating adherence of theparticles during the immersion step.

In certain embodiments, in steps b, c and e, immersion is carried outfor 5 to 10 minutes each, at a temperature between 50° C. and 70° C. Incertain embodiments, immersion is carried out for 5 to 10 minutes each,at approx. 60° C.

In certain embodiments, drying comprises drying in an oven at 60° C. to80° C. for 2 to 20 minutes. In certain embodiments, drying is carriedout for 5 to 15 minutes. In certain embodiments, drying is carried outfor approx. 10 minutes.

In certain embodiments, a chlorination step, in which the latex cover isexposed to chlorine, is performed after removal of the multi-layeredcover from the former. In this step, residues of the coagulator liquidare removed from the outer surface of the latex cover and the outersurface is smoothened.

In certain embodiments, the former is hand-shaped.

In certain embodiments, the former is pre-warmed to approx. 60° C. priorto step b.

In certain embodiments, the particles are pre-warmed to approx. 60° C.prior to their application.

In certain embodiments, the coagulator liquid comprises sodium chlorideas a coagulator. In certain embodiments, the coagulator liquid comprisesacetic acid, calcium chloride, calcium nitrate, formic acid, zincnitrate, or a mixture thereof as a coagulator.

In certain embodiments, the coagulator liquid is an aqueous solution ofCa(NO₃)₂. In certain embodiments, the coagulator liquid is an aqueoussolution of NaCl. In certain embodiments, the coagulator liquid is anaqueous solution of Na₂CO₃. In certain embodiments, the coagulatorliquid is an aqueous solution of KNaC₄H₄O₆. In certain embodiments, thecoagulator liquid is an aqueous solution of MgSO₄.

Within the context of the present specification, the concentration ofcalcium nitrate and calcium carbonate is given in % (v/v). The mass ofthe substances weighed in (Ca(NO₃)₂*4H₂O or CaCO₃) has been converted toa volume taking into account the density of the substances.

In certain embodiments, the concentration of calcium nitrate in thecoagulator liquid ranges from 0.14% to 18.3% (v/v (the calcium partbeing calculated on the basis of Ca(NO3)2*4H2O). This equals aconcentration range of approx. 10 mmol/l to approx. 1.4 mol/l. Incertain embodiments, the concentration of Ca(NO₃)₂*4H₂O ranges from 0.5%to 3% (v/v). In certain embodiments, the concentration of Ca(NO₃)₂*4H₂Ois approx. 2.3% (v/v). The inventors have demonstrated that a calciumnitrate concentration of 2.3% (v/v) is preferable.

In certain embodiments, the coagulator liquid comprises a former releaseagent. Within the context of the present specification, the term “formerrelease agent” refers to a substance that prevents the latex frompermanently adhering to the former and enables/facilitates the removalof the multi-layered cover from the former at the end of the productionprocess. The former release agent also prevents conglutination of theprotective latex cover after removal from the former.

In certain embodiments, the former release agent is magnesium carbonate.In certain embodiments, the former release agent is sodium chloride. Incertain embodiments, the former release agent is polydimethylsiloxane.In certain embodiments, the former release agent is a polyalkylene oxidemodified diethylpolysiloxane. In certain embodiments, the former releaseagent is a stearic acid or stearate. In certain embodiments, the formerrelease agent is selected from fatty acids, metal oxides, in particularzinc oxide, ethylenes, in particular ethylenebisoleamide, glycols, inparticular polyethylene glycols and polyalkylene glycols, ammonium saltsof alkyl phosphate, polyethylenes, glycerine, amorphous polypropylene,and unbranched alcohols.

In certain embodiments, the former release agent is calcium carbonate.In certain embodiments, the concentration of calcium carbonate in thecoagulator liquid is approx. 10% (v/v). This equals a concentration ofapprox. 2.7 mol/l. In certain embodiments, the calcium carbonate is inthe form of calcium carbonate particles having a mean diameter of <30μm.

In certain embodiments, the first and second latex dispersions comprise25% to 70% (v/v) latex. The latex may be natural or synthetic latex.

In certain embodiments, the latex content of the second latex dispersionis lower than the latex content of the first latex dispersion. Thisresults in a second latex layer that is thinner than the first latexlayer. In certain embodiments, the first latex dispersion comprisesapprox. 60% (v/v) latex and the second latex dispersion comprisesapprox. 30% (v/v) latex. In general, the use of latex dispersions with ahigh latex concentration results in a better separation of the first andsecond layers. The latex concentrations can be lower than stated aboveif steps c and f are repeated, i.e. performed two or three times. Ifstep c is repeated twice, the first latex dispersion may be as low as30% (v/v). If step c is repeated three times, the first latex dispersionmay be as low as 20% (v/v). If step f is repeated twice, the secondlatex dispersion may be as low as 15% (v/v). If step c is repeated threetimes, the second latex dispersion may be as low as 10% (v/v).

In certain embodiments, the first and second latex dispersions comprise0.2% to 5% (v/v) NH₃. In certain embodiments, the first and second latexdispersions comprise approx. 3% (v/v) NH₃.

In certain embodiments, the second latex dispersion comprises acolouring agent. In certain embodiments, the first latex dispersioncomprises a colouring agent. In certain embodiments, the colouring agentis Uranin or Heliogen Blue. In the context of the present specification,the term “Uranin” refers to the disodium salt form of the compoundfluorescein (CAS No. of fluorescein: 2321-07-5). Uranin is also known as“D&C Yellow no. 8”. In the context of the present specification, theterm “Heliogen Blue” refers to a colouring agent based on the compoundspecified by the molecular formula C₃₂H₁₆CuN₈ ⁻⁴ (PubChem CID:54609463). Non-limiting examples of such colouring agents are HeliogenBlue 7560, Heliogen Blue 7800, Heliogen Blue D 7490, Heliogen Blue D7560, Heliogen Blue D 7565, Heliogen Blue G, Heliogen Blue L 7460,Heliogen Blue L 7560 and Heliogen Blue LG.

If a perforation occurs in the outer latex layer, prevailing moisture,e.g. from a wet environment or from the surrounding air, will enterthrough the perforation and will accumulate between the outer and innerlatex layer, in other words the water/moisture will accumulate in theintermediate (particle) layer. Via capillary action, the outer and innerlatex layer will visibly agglutinate/stick together and the perceivedcolour will be that of the inner layer. This visible effect is morepronounced if the contrast between the outer and the inner latex layeris high. In instances where a breach indicator function is desired, itis thus beneficial to include colouring agents in the outer and/or innerlatex layers and/or particles. It is obvious to the skilled person thatin instances where a breach indicator function is desired, both innerand outer latex layers have to be initially liquid- and air-impermeableand only become permeable if they are perforated, e.g. accidentally orby tampering.

In certain embodiments, the first and second latex dispersions comprisea vulcanization system. Addition of a vulcanization system improveshardening of the latex and provides protection against possible futuredeterioration of the latex. During vulcanization, the latex is modifiedby the formation of cross-links between individual polymer chains. Incertain embodiments, the vulcanization system is a sulfur curing system.In certain embodiments, the vulcanization system comprises sulfur, zincoxide, preservative substances and antioxidants. In instances where avulcanization system is used, a vulcanization step is carried outfollowing retraction of the particle treated former from the secondlatex dispersion in step e. The vulcanization step is carried out at atemperature between 120° C. and 200° C., in particular at approx. 140°C.

An alternative aspect of the invention relates to the method describedabove, wherein the second latex dispersion comprises bubbles, thusyielding a perforated second/inner latex layer. It is obvious to theskilled person that in instances where a perforated inner latex layer isdesired, a breach indicator function depending on capillary action is nolonger possible.

Alternatively, the method is conducted as outlined above, and a thirdlatex layer is added. In certain embodiments, the third latex layer isapplied using a latex solution comprising bubbles.

In certain embodiments, the method comprises the additional steps e2 ande3 subsequently to step e and prior to step f:

-   -   e2. Immersing the second latex covered former in a coagulator        liquid to an immersion depth d3, then retracting and drying the        second latex covered former.    -   e3. Immersing the second latex covered former in a third latex        dispersion comprising bubbles, to an immersion depth d2, then        retracting and drying the second latex covered former, yielding        a third latex covered former.

In these instances, the method yields a multi-layered latex cover,comprising a perforated inner latex layer and a non-perforated middleand outer latex layer, the latter two supporting the breach indicatorfunction. In step f, the word “second” is to be replaced by “third”.

In certain embodiments, steps d. and e are repeated several times,yielding a multi-layered latex cover with three or more latex layers.The inner latex layer or the inner latex layer and adjacent latex layersmay be intentionally perforated.

In certain embodiments, the method comprises a step d2 subsequently tostep d and previous to step e, wherein step d2 comprisescleaning/stripping discrete regions from said particles (and, ininstances where a second coagulator liquid was used, from said secondcoagulator liquid or dried remnants of it).

In certain embodiments, an adhesive cover is applied to the former afterthe first latex dipping, covering discrete regions and said adhesivecover is peeled off after application of the particles.

Both approaches result in discrete regions, e.g. the fingertips, thatare free of particles.

The discrete particle-free regions locally avoid separation of the latexlayers and the latex layers agglutinate at these discrete regions (FIG.6). Agglutination of the layers prevents slippage and improves thetactile sense of the person wearing the glove.

In certain embodiments, the discrete regions are regions of 1 mm² to 5cm² at each fingertip. In certain embodiments, the discrete regions areregions of 4 mm² to 2.5 cm². In certain embodiments, the discreteregions are regions of 9 mm² to 1 cm² at each fingertip. In certainembodiments, the discrete regions are regions of approx. 25 mm² at eachfingertip.

In certain embodiments, the discrete regions form patterns, signs,characters or numbers.

In certain embodiments, the first and second latex dispersions and thechemically functionalized particles comprise a vulcanization system.Following retraction of the particle treated former from the secondlatex dispersion in step e, a vulcanization step is carried out at atemperature between 100° C. and 200° C., in particular at approx. 140°C.

In certain embodiments, steps d and e are repeated several times,yielding a multi-layered latex cover having more than two latex layers.

In certain embodiments, silica particles are employed as particles,particularly in the size ranges given previously as particularembodiments of the former.

In certain embodiments, the particles are functionalized by covalentattachment to the surface of a compound selected from7-octenyltrimethoxysilane, 5-hexenyltrimethoxysilane,3-mercaptopropyltrimethoxysilane, 3-amino propyl)triethoxysilane,tris(2-methoxyethoxy)(vinyl)silane, allyltrimethoxysilane,3-(aminopropyl)triethoxysilane, hexadecyltrimethoxysilane,vinyltrimethoxy silane, triethoxyvinylsilane,3-trimethoxysilyl-propane-1-thiol, bis[3-(triethoxysilyl)propyl]tetrasulfide, 3-(methacryloxypropyl)trimethoxy-silane and3-N-(3-triethoxysilylpropyl)gluconamide.

In certain embodiments, the particles are additionally functionalized bycovalent attachment of a second compound selected from polyethyleneglycol, polyglycerol, N-(3-triethoxysilylpropyl)gluconamide and3-[methoxy(polyethylene oxy)propyl]trimethoxysilane.

The skilled person understands that the mentioned silanes will form,depending on reaction conditions, predominantly single, but also doubleor even triple bonds to the silica (or other solid) particle surfacecomprising OH moieties.

Wherever alternatives for single separable features are laid out hereinas “embodiments”, it is to be understood that such alternatives may becombined freely to form discrete embodiments of the invention disclosedherein.

The invention is further illustrated by the following examples andfigures, from which further embodiments and advantages can be drawn.These examples are meant to illustrate the invention but not to limitits scope.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates the immersion depth during the dipping process. 1:former, 2: first coagulator liquid, 3: first latex dispersion/firstlatex layer, 4: particle suspension, 5: second latex dispersion/secondlatex layer, d₁-d₄: immersion depth.

FIG. 2 shows a double-layered latex glove on a former at the end of thedipping process. The different layers of the glove are indicated in theleft-hand circles. 1: former, 2: coagulator layer, 3: first latex layer,4: particle layer, 5: second latex layer. The upper circle shows aregion of the glove in which first and second latex layers areagglutinated. The lower circle shows a region of the glove in whichfirst and second latex layers are separated.

FIG. 3 shows silica particles that are positioned between inner andouter latex layer. The particles are anchored in the inner latex layer.

FIG. 4 shows a double layered finger cot. Arrows indicate theagglutinated and separated regions (a) and the cross-section (outer andinner layers, b).

FIG. 5 shows a latex layer, which was dip-coated with functionalizedsilica particles and washed with a water-ethanol mixture. The particlesadhere to the latex layer. This status is an intermediate step for theproduction of a double-layered system with particles chemically linkedto one of the layers. Afterwards, this molding blank is furtherprocessed by dipping into the second latex dispersion, drying andvulcanization.

FIG. 6 shows a double layered finger cot with an agglutinated fingertip.

FIG. 7 shows the diagrams referred to in Example 1

FIG. 8 shows infrared spectra measured using Diffuse ReflectanceInfrared Fourier Transform Spectroscopy (in KBr pellets) of i) silicaparticles functionalized with triethoxyvinylsilane (VTES) and PEG2000and ii) silica particles with VTES only. Bands of VTES (grey) andPEG2000 (white) are marked in the IR spectra.

FIG. 9 shows dip-coated multi-layered covers comprising two naturalrubber layers and an intermediate layer of functionalized silicaparticles.

-   -   a) Time-dependent influx of a water droplet (2 s, 10 s, 20 s, 30        s, 40 s, 50 s, 60 s, 120 s, 180 s after perforation) shown for        covers containing silica particles functionalized with VTES        +PEG2000.    -   b) Perforation indicator effectiveness (PIE, effective area of        changing color over time) in dependence of surface        functionalization of silica particles (triethoxyvinylsilane        (VTES) +PEG2000, VTES, 3-(aminopropyl)triethoxysilane (APTES)).    -   c) Light-microscopy images of the cross-section of the covers        showing the outer layer (1), the inner layer (2) and the        intermediate layer of silica particles functionalized with VTES        +PEG2000, VTES and APTES.

FIG. 10 exemplarily shows water droplets on natural rubber surfacescovered with functionalized silica particles and the resulting contactangle in dependence of surface functionalization of silica particles(triethoxyvinylsilane (VTES) +PEG2000, VTES,3-(aminopropyl)triethoxysilane (APTES).

EXAMPLES Example 1 A Optimization of Calcium Nitrate Concentration(Diagram FIG. 7 A)

The effect of the calcium nitrate concentration [% (v/v), calculated onthe basis of Ca(NO₃)₂*4H₂O] on the thickness of a single latex layer wasanalysed. Latex: 60% (v/v); calcium carbonate: 10% (v/v).

Example 1 B Optimization of Calcium Carbonate Concentration (DiagramFIG. 7 B)

The effect of the calcium carbonate concentration [% (v/v)] on thethickness of a single latex layer was analysed. Latex: 60% (v/v);calcium nitrate: 2.3% (v/v).

Example 1 C Optimization of Latex Dispersion (Diagram FIG. 7 C)

The effect of the latex concentration [% (v/v)] on the thickness of asingle latex layer was analysed. Calcium carbonate: 10% (v/v); calciumnitrate: 2.3% (v/v).

Standard Protocol for Glove Production According to the Invention

-   1) Coagulator with release agent solution, exemplarily:    -   1.5 I water    -   110 g calcium nitrate    -   600 g calcium carbonate (CaCO₃)-   2) Concentration Latex 1: 30%-   3) Silica particle suspension-   4) Concentration Latex 2: 60%

Particle Functionalization with Silanes

(exemplarily described for 1 g of particles andtris(2-methoxyethoxy)(vinyl)silane as silane)

-   1. Silica particles are suspended in 30 ml of Ethanol and 30 ml of    NaOH solution (1 mol l⁻¹) and treated by ultrasound.-   2. 10 ml of Ethanol, 10 ml of NaOH solution (1 mol l⁻¹) and 5 ml of    silane are added.-   3. The solution is stirred for 2 h at room temperature.-   4. The particles were centrifuged and washed for two times with    ethanol.-   5. The suspension was dried at 30° C. for 12 hours.-   6. The particles were mechanically threated to get a powder.-   7. The particles are suspended in a mixture of 70% water and 30%    alcohol.

Particle Functionalization with Either PEG or Silanes

SiO₂ particles were suspended in water and mixed with the appropriateamount of silane or PEG. The pH was adjusted to 9-10 and the suspensionwas stirred at 75° C. for about 2-4 h. The dispersion was then dried at75° C. for several hours to remove the solvent. The powder was thenwashed twice each with H₂O and EtOH and centrifuged. The resultingparticles were dried at 75° C. for several hours to obtain the finalproduct.

Particle Functionalization with PEG and Silanes

As PEG, PEG200, PEG2000, PEG10000, PEG20000 and more were used. Assilanes, one of the following were employed:tris(2-methoxyethoxy)(vinyl)silane, allyltrimethoxysilane,3-(aminopropyl)triethoxysilane, hexadecyltrimethoxysilane,vinyltrimethoxysilane, triethoxyvinyl silane,3-trimethoxysilylpropane-1-thiol,bis[3-(triethoxysilyl)propyl]tetrasulfide, 3-(methacryloxypropyl)trimethoxysilane,3-[methoxy(polyethyleneoxy)propyl]trimethoxysilane,N-(3-triethoxysilylpropyl)gluconamide.

The reaction was carried out as follows:

A corresponding amount of silane (10 mol % or above) was added to asuspension of silica particles in H₂O/EtOH (1:1 v/v). After adjustingthe pH to 9-10 (NaOH or NH₄OH) the suspension was stirred for 5 min.Afterwards PEG (between 10 and 70 mol %) was added and the reactionmixture was stirred until PEG was dissolved. The mixture was thenstirred at 75° C. for 8 h. After removing the solvent, the particleswere washed with H₂O and EtOH several times to remove unreactedcompounds. The particles were then dried at 70° C. for 24 h to obtainthe final product.

Measuring Instructions for Perforation Indicator Effectiveness (PIE)

-   -   1. Place double-layered cover on an coloured former    -   2. Puncture with needle    -   3. Place water drop on top of perforation (excess water)    -   4. Trigger water inflow by application of slight mechanical        stress parallel to the layers (strain the perforation)    -   5. Take pictures with a defined length scale for calibration and        after a defined period of time (2 s, 10 s, 20 s, 30 s, 40 s, 50        s, 60 s, 120 s, 180 s after perforations).    -   6. Quantify the PIE by measuring the affected area with        image-processing, e.g. by the help of the software ImageJ        (Schneider, C. A.; Rasband, W. S.; Eliceiri, K. W. (2012),        Nature methods 9(7):671-675). Make sure to only consider water        in between the layers, not in between latex and former.

Contact Angle Measurements

Contact angles were determined using a Kyowa Dropmeter (DMs-401)equipped with a 32 G needle from stainless steel. Drops of 2.0 μl ofpurified water were placed on horizontally aligned sample surfaces(sessile drop technique). A picture was taken and evaluated 10 s aftersurface deposition of the drop. Data acquisition and analysis wasperformed using the half-angle method in the interFAce Measurement andAnalysis Software FAMAS.

Material

-   Neotex FA: natural latex, full ammonia, 60% Polyisopren with natural    associated material-   ProChemie-Latex: 60%, FA, Polyisopren with natural associated    material-   Vulcanizer: Suprotex L 4204-2, Weserland.eu-   Calcium carbonate (CaCO₃), CAS-No. 471-34-1, S3-Chemicals-   Calcium nitrate tetrahydrate (Ca(NO₃)₂*4H₂O), CAS-No. 13477-34-4,    S3-Chemicals, 98%-   Talcum powder: diacleanshop, CAS-No. 14807-96-6, EG-No. 238-877-9-   Silica particles: Kremer Pigmente, spheric, <50 μm-   Silica particles, fumed, CAS 112945-52-5, Sigma Aldrich 0.007 μm-   Silica particles, fumed, CAS 112945-52-5, Sigma Aldrich 0.2-0.3 μm-   Silica particles: Fumed silica OX50 (Aerosil®), CAS 112 945-52-5,    (ex 7631-86-9)-   Tris(2-methoxyethoxy)(vinyl)silane, CAS 1067-53-4, Sigma Aldrich-   Allyltrimethoxysilane, CAS 2551-83-9, ABCR-   3-(Aminopropyl)triethoxysilane, CAS 919-30-2, Sigma Aldrich-   Hexadecyltrimethoxysilane, CAS 16415-12-06, Sigma Aldrich-   Vinyltrimethoxysilane, CAS 2768-02-7, Sigma Aldrich-   Triethoxyvinylsilane, CAS 78-08-0, Merck-   3-Trimethoxysilylpropane-1-thiol, CAS 4420-74-0, Evonik-   Bis[3-(triethoxysilyl)propyl]tetrasulfide, CAS 40372-72-3, ABCR-   3-(Methacryloxypropyl)trimethoxysilane, CAS 2530-85-0, ABCR-   3-[Methoxy(polyethyleneoxy)propyl]trimethoxysilane, CAS 65994-07-2,    ABCR-   N-(3-triethoxysilylpropyl)gluconamide, CAS 104275-58-3, ABCR-   Heliogen® Blau: Kremer Pigmente, blue pigment-   Uranin: Kremer Pigmente, yellow pigment-   PEG 200, PEG 2000, PEG 10000, PEG 20000, CAS 25322-68-3, Carl Roth

1. A multi-layered cover, particularly a glove for a human hand,comprising a main body and a rim, wherein said main body comprises a. anouter latex layer b. an inner latex layer c. an intermediate layercomprising particles, wherein said particles are characterized by i. amean diameter of 100 μm and ii. a surface comprising exposed OH groupswhen in a non-functionalized state; and said rim essentially consists ofthe agglutinated outer and inner latex layer, characterized in that saidparticles are chemically functionalized with a compound comprisinghydrophobic groups.
 2. The multi-layered cover according to claim 1,wherein said particles comprise or essentially consist of inorganicparticles, in particular particles made from silica, titanium dioxide orzirconium dioxide, more particularly particles made from silica.
 3. Themulti-layered cover according to any one of the preceding claims,wherein said particles are characterized by a. a mean diameter of ≤10μm, more particularly a mean diameter of ≤1 μm, even more particularly amean diameter of ≤0.1 μm, or b. ≤90% of said particles having a diameterof ≤10 μm, more particularly 90% of said particles having a diameter of≤1 μm, even more particularly 90% of said particles having a diameter of≤0.1 μm
 4. The multi-layered cover according to any one of the precedingclaims, wherein said particles are characterized by a surface comprisingexposed OH groups having a density of 2-5 mnm², in particular 2.2-2.5/nm².
 5. The multi-layered cover according to any one of the precedingclaims, wherein said compound comprising hydrophobic groups is acompound comprising a. an unsaturated group, particularly an unsaturatedcarbon-carbon double bond, more particularly a CHCH₂ moiety, or b.sulfur, particularly wherein said compound comprising hydrophobic groupsis selected from 7-octenyltrimethoxysilane, 5-hexenyltrimethoxysilane,3-mercaptopropyltrimethoxy-silane, 3-(aminopropyl) triethoxysilane,tris(2-methoxyethoxy)(vinyl)silane, allyltrimethoxysilane, 3-(aminopropyl)triethoxysilane, hexadecyltrimethoxysilane,vinyltrimethoxysilane, triethoxyvinyl silane,3-trimethoxysilylpropane-1-thiol,bis[3-(triethoxysilyl)propyl]tetrasulfide,3-(methacryloxypropyl)trimethoxysilane and3-N-(3-triethoxysilylpropyl)gluconamide.
 6. The multi-layered coveraccording to any one of the preceding claims, wherein saidfunctionalized particles have an at least partially hydrophobic surface.7. The multi-layered cover according to any one of the preceding claims,wherein said particles are additionally functionalized with a compoundcomprising hydrophilic groups, particularly selected from polyethyleneglycol, polyglycerol, and N-(3-triethoxysilylpropyl)gluconamide or3-[methoxy(polyethyleneoxy)propyl]trimethoxy-silane.
 8. Themulti-layered cover according to any one of the preceding claims,wherein said functionalized particle has an amphiphilic particlesurface.
 9. The multi-layered cover according to any one of thepreceding claims, wherein said particles are functionalized with atleast two different compounds.
 10. The multi-layered cover according toclaim 9, wherein a. a first compound is selected from compounds suitablefor yielding a hydrophobic surface, in particular the first compound isa compound comprising an unsaturated group (more particularly a CH═CH₂moiety) or sulfur, more particularly a compound selected from7-octenyltrimethoxysilane, 5-hexenyltrimethoxysilane,3-mercaptopropyltrimethoxysilane, 3-amino propyl)triethoxysilane,tris(2-methoxyethoxy)(vinyl)silane, allyltrimethoxysilane,3-(aminopropyl)triethoxysilane, hexadecyltrimethoxysilane,vinyltrimethoxy silane, triethoxyvinylsilane,3-trimethoxysilylpropane-1-thiol, bis[3-(triethoxysilyl)propyl]tetrasulfide, 3-(methacryloxypropyl)trimethoxysilane and3-N-(3-triethoxysilylpropyl)gluconamide, and b. a second compound isselected from compounds suitable for yielding a hydrophilic surface, inparticular a substance selected from polyethylene glycol, polyglycerol,N-(3-triethoxysilylpropyl)gluconamide and 3-[methoxy(polyethyleneoxy)propyl]trimethoxysilane.
 11. The multi-layered cover according toany one of the preceding claims, wherein said particles are chemicallylinked to the inner and/or outer latex layer, particularly to the faceof the latex layer facing the intermediate layer.
 12. The multi-layeredcover according to any one of the preceding claims, wherein said innerand/or outer latex layer is characterized by a contact angle with waterof <90°, particularly <45°, on a face of the latex layer facing theintermediate layer.
 13. The multi-layered cover according to any one ofthe preceding claims, wherein said multi-layered cover is characterizedby a thickness of 100 μm to 800 μm uniformly extending across its entiredimensions.
 14. The multi-layered cover according to any one of thepreceding claims, wherein said outer layer and said inner latex layerare agglutinated at discrete regions, particularly at regions of 1 mm²to 5 cm², more particularly regions of 4 mm² to 2.5 cm², even moreparticularly regions of 9 mm² to 1 cm², more particularly approx. 25 mm²at each fingertip.
 15. The multi-layered cover according to claim 14,wherein said discrete regions form patterns, signs, characters ornumbers.
 16. The multi-layered latex cover according to any one of thepreceding claims, wherein said intermediate layer comprises a pluralityof double layers comprising a. particles having a mean diameter of 100μm and a surface comprising exposed OH groups, wherein said particlesare chemically functionalized with a compound comprising hydrophobicgroups, and b. a latex layer.
 17. A multi-layered latex cover accordingto claim 16, wherein the inner latex layer, or the inner latex layer andadjacent latex layers of the intermediate layer are perforated.
 18. Aglove comprising or essentially consisting of a multi-layered coveraccording to any one of claims 1 to
 17. 19. A method of producing amulti-layered cover, comprising the steps of: a. providing a former,particularly a former having the shape of a human hand; b. immersingsaid former in a first coagulator liquid, to an immersion depth d₁, thenretracting and drying said former; c. immersing said former in a firstlatex dispersion to an immersion depth d₂, then retracting and dryingsaid former, yielding a first latex covered former; d. applyingchemically functionalized particles to said first latex covered formerto an immersion depth d₃; yielding a particle treated former; whereinsaid particles are in a non-functionalized state characterized by a meandiameter of 100 μm and a surface comprising exposed OH groups,particularly at a density of 2-5 mnm², more particularly 2.2-2.5 /nm²,and chemically functionalized with a compound comprising hydrophobicgroups; e. immersing said particle treated former in a second latexdispersion to an immersion depth d₄, then retracting and drying saidparticle treated former; yielding a second latex covered former, whereind₁≥d₂>d₃ and d₁≥d₄>d₃; f. removing the applied layers from said coatedformer, yielding said multi-layered cover.
 20. The method according toclaim 19, wherein between step e and f, a step is performed whereby acoating is applied to said second latex covered former, yielding acoated former.
 21. The method according to claim 19 or 20, wherein saidstep d is effected by immersing said first latex covered former in anaqueous suspension comprising chemically functionalized particles at aconcentration of between 0.2 and 7 mol/L, particularly approx. 1 mol/Lto an immersion depth d₃.
 22. The method according to any one of claims19 to 21, wherein said chemically functionalized particles are appliedin step d from an aqueous suspension with a concentration of 0.2 and 7mol/L, particularly approx. 1 mol/L by adding a latex dispersion (40-80wt %, particularly 60 wt % solid content) with a volume ratio ofsuspension to latex dispersion of less than 1:20.
 23. The methodaccording to any one of claims 19 to 22, wherein discrete regions arecleaned from said chemically functionalized particles subsequently tostep d and previous to step e.
 24. The method according to any one ofclaims 19 to 22, wherein an adhesive cover covering discrete regions isapplied to the former subsequently to step c and prior to step d, andpeeled off after step d.
 25. The method according to claim 23 or 24,wherein said discrete regions are regions of 1 mm² to 5 cm² to, moreparticularly regions of 4 mm² to 2.5 cm², even more particularly regionsof 9 mm² to 1 cm², more particularly approx. 25 mm² at each fingertip.26. The method according to claim 25, wherein said discrete regions formagglutinated patterns, signs, characters or numbers.
 27. The methodaccording to any one of claims 19 to 26, wherein said first and secondlatex dispersions and the chemically functionalized particles comprise avulcanization system, and wherein following retraction of said particletreated former from said second latex dispersion in step e, avulcanization step is carried out at a temperature between 100° C. and200° C., in particular at approx. 140° C.
 28. The method according toany one of claims 19 to 27, wherein steps d and e are repeated severaltimes, yielding a multi-layered latex cover having more than two latexlayers.
 29. The method according to any one of claims 19 to 28, whereinsaid particles are silica particles.
 30. The method according to any oneof claims 19 to 29, wherein said particles are functionalized bycovalent attachment to the surface of a compound selected from7-octenyltrimethoxysilane, 5-hexenyltrimethoxysilane,3-mercaptopropyltrimethoxy-silane, 3-amino propyl)triethoxysilane,tris(2-methoxyethoxy)(vinyl)silane, allyl-trimethoxysilane,3-(aminopropyl)triethoxysilane, hexadecyltrimethoxysilane,vinyltrimethoxy silane, triethoxyvinylsilane,3-trimethoxysilylpropane-1-thiol, bis[3-(triethoxysilyl)propyl]tetrasulfide, 3-(methacryloxypropyl)trimethoxysilane and3-N-(3-triethoxysilylpropyl)gluconamide.
 31. The method according toclaim 30, wherein said particles are additionally functionalized bycovalent attachment of a second compound selected from polyethyleneglycol, polyglycerol, N-(3-triethoxysilylpropyl)gluconamide and3-[methoxy(polyethylene oxy)propyl]trimethoxysilane